Being such a short distance from the cabinet and exchange it beggars belief I can see it from my window!!
The decision about whether to upgrade a cabinet is usually based on a combination of the ease with which fibre and power can get to the cabinet (and fibre itself doesn't sound onerous in your case) and physically locating the new cabinet *and* how many properties will benefit from the upgrade.
In the case of cab 9, it looks like a lot of the properties served are more than 1.5km from the cabinet, so won't be able to benefit from superfast speeds.
The calculation of "value for money" is done based on the cost per property-benefitting. It sounds like BT and/or SC have determined that the money is better spent elsewhere - and have chosen not to include your cabinet in the programme. Yet...